1. Field of the Invention
The present invention relates to low-temperature and heatresistant materials for reducing noise and for protection against weathering effects, corrosion and stone chipping, which can be used, in particular, in the underfloor region of motor vehicles.
2. Discussion of the Background
At present, underfloor protective materials for motor vehicles are still predominantly PVC plastisols which, as a rule, are sprayed by the "airless method" and then gelled. These systems have an adequate low-temperature resistance, heat resistance and abrasion resistance, and offer adequate corrosion protection.
The market has recently been imposing requirements in relation to recycling capability in addition to requirements relating to the material properties themselves, and at the same time, demanding the restriction to as few types of plastics as possible. Thus, it has become necessary to develop a protective material which is mainly based on poly-.alpha.-olefins, since poly-.alpha.-olefins are already being used to an ever-increasing extent in other motor vehicle parts (for example, bumpers, cooling water compensation reservoirs, heating and ventilating systems). In particular, a protective material capable of application in molten form is also of interest, because it can be applied directly to the bodywork emerging hot from electrophoretic painting. Consequently, the energy-consuming steps of cooling and reheating of the bodywork, necessary for the application of PVC plastisols hitherto mainly used for this purpose, is superfluous. Therefore, both energy and time can be saved by use of a protective material based on poly-.alpha.-olefins.
Although various efforts have already been made in the past to develop such systems, the pattern of properties is generally too unbalanced. In particular, resin-containing hot melts, bitumen-containing systems or rubber-based, oil- and filler-containing materials are usually involved. In this connection, the resin-containing hot melts exhibit inadequate heat resistance as an important disadvantage. Bitumen-containing materials have the same disadvantage and are, in addition, too soft, while the adhesion is a problem in the case of oil- and filler-containing, rubber-based materials.
Amorphous poly-.alpha.-olefins such as, for example, atactic polypropylene, have also already been tested for this purpose. Apart from the fact that their mechanical properties did not meet the requirements, these amorphous poly-.alpha.-olefins were combined, for example, with resins, oils, bitumen, etc., and then additionally exhibited the disadvantages already mentioned above for these materials, such as inadequate heat resistance and hardness.
Thus, there remains a need for a composition which can reduce noise and protect metal against the effects of weather, corrosion and mechanical damage, such as that caused by collision with small debris. Further, the need to produce such a composition from materials which can be applied in an energy saving manner and which can be easily recycled is also strongly felt.